padding zero for sparse file

weed/filer/reader_at.go

@@ -129,7 +129,7 @@ func (c *ChunkReadAt) doReadAt(p []byte, offset int64) (n int, err error) {
 		}
 		if startOffset < chunk.LogicOffset {
 			gap := int(chunk.LogicOffset - startOffset)
-			glog.V(4).Infof("zero [%d,%d)", startOffset, startOffset+int64(gap))
+			glog.V(4).Infof("zero [%d,%d)", startOffset, chunk.LogicOffset)
 			n += int(min(int64(gap), remaining))
 			startOffset, remaining = chunk.LogicOffset, remaining-int64(gap)
 			if remaining <= 0 {

weed/filer/stream.go

@@ -80,11 +80,23 @@ func StreamContent(masterClient wdclient.HasLookupFileIdFunction, writer io.Writ
 		fileId2Url[chunkView.FileId] = urlStrings
 	}
 
+	remaining := size
 	for _, chunkView := range chunkViews {
-
+		if offset < chunkView.LogicOffset {
+			gap := chunkView.LogicOffset - offset
+			remaining -= gap
+			glog.V(4).Infof("zero [%d,%d)", offset, chunkView.LogicOffset)
+			err := writeZero(writer, gap)
+			if err != nil {
+				return fmt.Errorf("write zero [%d,%d)", offset, chunkView.LogicOffset)
+			}
+			offset = chunkView.LogicOffset
+		}
 		urlStrings := fileId2Url[chunkView.FileId]
 		start := time.Now()
 		err := retriedStreamFetchChunkData(writer, urlStrings, chunkView.CipherKey, chunkView.IsGzipped, chunkView.IsFullChunk(), chunkView.Offset, int(chunkView.Size))
+		offset += int64(chunkView.Size)
+		remaining -= int64(chunkView.Size)
 		stats.FilerRequestHistogram.WithLabelValues("chunkDownload").Observe(time.Since(start).Seconds())
 		if err != nil {
 			stats.FilerRequestCounter.WithLabelValues("chunkDownloadError").Inc()
@@ -92,6 +104,11 @@ func StreamContent(masterClient wdclient.HasLookupFileIdFunction, writer io.Writ
 		}
 		stats.FilerRequestCounter.WithLabelValues("chunkDownload").Inc()
 	}
+	glog.V(4).Infof("zero [%d,%d)", offset, offset+remaining)
+	err := writeZero(writer, remaining)
+	if err != nil {
+		return fmt.Errorf("write zero [%d,%d)", offset, offset+remaining)
+	}
 
 	return nil
 
@@ -99,6 +116,23 @@ func StreamContent(masterClient wdclient.HasLookupFileIdFunction, writer io.Writ
 
 // ----------------  ReadAllReader ----------------------------------
 
+func writeZero(w io.Writer, size int64) (err error) {
+	zeroPadding := make([]byte, 1024)
+	var written int
+	for size > 0 {
+		if size > 1024 {
+			written, err = w.Write(zeroPadding)
+		} else {
+			written, err = w.Write(zeroPadding[:size])
+		}
+		size -= int64(written)
+		if err != nil {
+			return
+		}
+	}
+	return
+}
+
 func ReadAll(masterClient *wdclient.MasterClient, chunks []*filer_pb.FileChunk) ([]byte, error) {
 
 	buffer := bytes.Buffer{}